Abstract

Two experiments revealed how non-experts interpret visualizations
of positional uncertainty on GPS-like displays and how the visual representation
of uncertainty affects their judgments. Participants were shown maps with
representations of their current location; locational uncertainty was visualized
as either a circle (confidence interval) or a faded glyph (indicating the
probability density function directly). When shown a single circle or faded
glyph, participants assumed they were located at the center of the uncertain
region. In a task that required combining two uncertain estimates of their
location, the most common strategy – integration – was to take both
estimates into account, with more weight given to the more certain estimate.
Participants’ strategies were not affected by how uncertainty was
visualized, but visualization affected the consistency of their responses. The
results indicate that non-experts have an intuitive understanding of uncertainty
and that the best visualization method is task dependent.